1. Field of the Invention
This invention relates to valves for use with a rod pump for venting fluid and gas passed up a tubing string during oil well pumping operations.
2. Prior Art
Crude oil production, particularly from old oil wells, often requires the use of artificial lift means by which the crude oil is lifted from the well bore to the surface. For this purpose a number of downhole pumps have been developed. All of which pumps are subject to gas lock when they encounter and pump a mix of crude oil and natural gas solubilized therein. Gas locking is a common phenomenon that occurs within a pump that is moving a formation fluid where separation of the natural from the crude occurs. Gas locking is more likely to occur as the fluid level at the bottom of a well bore is lowered from pumping action.
To provide pumping to lift fluid out of a well downhole some commonly available pumps include a plunger that is reciprocated through a tubing string by operation of a pump jack. Which plunger includes a check valve assembly, that is generally known as a traveling valve assembly, which traveling valve assembly controls the flow of formation fluid through the plunger on the downstroke. The closure of the traveling valve assembly enables the plunger to lift fluid, on the upstroke.
The traveling valve assembly is opened by a solid column of fluid, on the downstroke, and functions to expel gas that has been entrained in the fluid along with passing the collected fluid. The traveling valve assembly then closes on the upstroke to lift fluid that has passed into the pump barrel. Over the years a number of valve arrangements have been developed as traveling valve assemblies, the present invention being an improvement thereover.
A recent U.S. Pat. No. 4,781,547 to Madden, is an example of a recent development in traveling valve assemblies. This patent cites and distinguishes a number of earlier traveling valve assemblies. All of which earlier traveling valve assemblies, as well as the Madden valve, are subject to failure from hydrostatic pressure present in the pumped fluid. Specifically, earlier valves have generally been found to be unsatisfactory due to their complexity of construction. Or, as to the Madden valve, have experienced failure from clogging due to materials lodging between the free ball and seat, prohibiting valve closure. Such valve failures have constituted a major and expensive problem in that, on valve failure, the entire tubing string must be pulled to effect valve repair or replacement. The neutralizer valve of the present invention provides a very simple valve arrangement whose operation is essentially unaffected by contamination of the crude oil passing therethrough. It is very simple in its construction in that it involves only a guide barrel containing a closure portion that is a ported seal stem whose upper end is tracked to move vertically only. Rather than a ball and seat, the present invention provides a fixed stem collar that is formed around the ported seal stem mid-section that includes a valve face for moving onto and off of a fixed seat that is secured in the guide barrel, passing fluid thereacross, with the ported seal stem the only moving part.